1. Field of the Invention
The present invention is related to an electric heater made from extruded aluminum members. The electric heater is light in weight, easily assembled, low in cost and quick in heating.
2. Description of the Prior Art
The general methods of increasing indoor temperature by heating conventionally includes "heating by radiation" and "heating by hot air convection". The burning of wood in a fireplace causes fire to emit heat into the ambient air via heat radiation. A heater that generates heat energy by burning wood can raise the temperature of ambient air around the heater and thus the temperature of a room as well by hot air convection.
As shown in FIG. 1, in a conventional electric heater, an arciform stainless steel plate 2 is provided in front of an iron housing 1. The stainless steel plate 2 is provided in a concave recess thereof with a plurality of quartz pipes 3. The quartz pipes 3 emit infrared light having heat energy after becoming electrically energized; the light is reflected by the stainless steel plate 2 to heat the area in front of the electric heater.
Such an electric heater is capable of generating radiation heat that is low in cost and in a short period of time. However, during the emission of heat, only the areas where the body of a person receives light can feel the warmth, and when the person receives the light for a prolonged period, dryness and discomfort for the user ensues.
As is shown in FIG. 2, a conventional convective electric heater that uses air convection to heat includes a heating portion 4, a connecting pipe line (not shown) and steel plates 5. The heating portion 4 is provided with a heater and a pump, and low-volatile oil stored therein. The oil can be heated gradually by the heater, and is delivered by the pump to the connecting pipe line to cause the cold oil in the connecting pipe line to be sent hack to the heating portion 4, thereby forming a circulation flow. The connecting pipe line is connected to the heating portion 4 and rounds about the sequentially arranged steel plates 5, and when the heated oil flows, the temperature in the steel plates 5 rises. When cool air flows through the steel plates 5, air is warmed by the surfaces of the steel plates 5 and flows upwardly. The temperature of a room can thus be raised gradually by air convection.
The advantage of the aforesaid air convection electric heater is that the temperature of a room can be raised steadily, and more uniformly as compared to heat radiation electric heaters but convection electrical heaters have the following disadvantages.
Since oil is heated in advance and pumped to the steel plates to heat the plates before heat convection can start, heating is very slow.
Structurally, a connecting pipe line must be provided to deliver hot oil without oil leakage, and thus the problem of expanding oil after heating must somehow be overcome. The structure thereof is thus complicated and the assembly thereof is difficult and time consuming, adding to the cost of production.
Since oil leakage due to oil expansion must be prevented, and the absorption and scattering of the heat from the hot oil must be carefully monitored, steel plates made of hardened steel must preferably be used and sequentially spaced. Due to the increased weight of the steel plates in addition to the weights of the oil pipe, the pump and the oil itself, this type of electric heater is too heavy, and is thus difficult to move.
The fact that the heating portion 4 must be provided with a connecting pipe line for delivering hot oil, it is not easy to simply increase or decrease the number of the steel plates and the amount of oil to manufacture a heater for various specifications and suitable for various space sizes. It may not be economical to purchase more electric heaters to provide heat.
Among the above mentioned disadvantages, consumers are generally attentive to the slowness of heating and many users utilize a fan to spread heat of a convective electric heater. The cause of the slow speed of heating a room with an electric heater is due to the way in which oil is heated in advance and pumped to the steel plates. This is an indirect method of heat conduction, thus the speed of heating is very low. Adding a fan to the convective electric heater can increase the speed of air convection but this results in added noise generated by the fan as well as costs associated with the fan.
Heat radiating electric heaters are limited by their heating method. They can only increase the size and power of the quartz pipes, for instance to increase the area of radiation or increase the amount of light emitted, but they cannot improve on their efficiency. There is a need to effectively improved the design of electric heaters to provide an electric heater which can increase heating speed, and which is easy to assemble economically.
Some prior art references for heaters provide a background for the invention. In U.S. Pat. No. 4,541,408 upright hollow pipes are used as a fence in front of the opening for a fire-space in a room, in order to receive the radiation energy from the fire-space and convert the energy into heat and in order to heat the air contained in the pipes. The device provides heat from a fire-space and it is not available for use without a fire-space and it is fixedly positioned in front of the opening of the fire-space and cannot be moved to other areas in the house.
UK patent GB2261723A, discloses a heater device that provides a body portion 1 with a heating element 15 and a fan 18. The fan 18 draws out hot air that is heated by the heating element 15 in the body portion. The disadvantages of using a fan has been previously discussed.
U.S. Pat. Nos. 1,701,096, 1,731,472, 1,840,598 and 1,895,482 are complex in design and difficult to assemble. Heat generating pipes are embedded in the complicated body structures adding to the cost of assembly. The pipes cannot be easily moved after being connected to the heat sources.
U.S. Pat. No. 4,900,898 discloses a heater that provides elongated incandescent ultraviolet lamps and a fan in a case. The fan draws air to the incandescent ultraviolet lamps via a plurality of walls and then to the space that is to be heated. The deficiencies of this device is similar to that of UK patent GB2261723A since it needs the assistance of a fan to conduct hot air outwardly and to increase the convection of air.
U.S. Pat. No. 2,530,058 includes deficiencies similar to that of the aforementioned U.S. Pat. Nos. 1,701,096, 1,731,472, 1,840,598 and 1,895,482, and due to its complexity, the cost of assembly will be high.
U.S. Pat. No. 3,396,458 discloses an electric heater with heat sinking fins at the exterior of a heat emitting member. This device is not for household use.